Quality assurance of drug prescription is a pre-requisite for rational drug use. From 22 health-care centres in the south-western area of the Stockholm County Council region, drug-prescription data were obtained from the patients' computerised medical recordings. This could be done with the aid of a specially designed database program. The drug-prescription data from the 22 health-care centres were collected and compiled in a central unit. Thereafter the results were brought back to the health-care centres, in which the quality assurance of drug prescription could be started.